Arbol chilies are a type of dried chili pepper that is commonly used in Mexican cuisine. They are small, thin, and bright red in color, with a very spicy flavor and heat that ranges from medium to very hot.

Here are some common uses of arbol chilies:

1. Flavoring: Commonly used to add a spicy, smoky flavor to sauces, salsas, soups, stews, and marinades.
2. Heat: Known for their intense heat, which can be adjusted to taste. They are often used in combination with milder chili peppers to balance out the heat.
3. Seasoning: Add flavor and heat to rubs for meat, poultry, and fish, as well as to spice up roasted vegetables.
4. Pickling: A popular ingredient in pickling recipes, as they add heat and flavor to pickled vegetables.
5. Powder: Can be ground into a fine powder and used as a spice for added heat and flavor in a variety of dishes.

When using arbol chilies in cooking, it is important to handle them with care, as they can irritate the skin and eyes. It is also important to remove the stems and seeds before using them, as these can be quite tough and bitter. To rehydrate dried arbol chilies, they can be soaked in hot water for 15-20 minutes before use. After rehydrating, the chilies can be blended into a paste or added directly to dishes for added flavor and heat.